Hydraulic piston and cylinder combination



June 14, 1960 o. MUELLER HYDRAULIC PISTON AND CYLINDER CQMBINATIQN Filed Dec. 6, 1957 p w \w M 124, a PF'IVL" Ms:

nited States Patent 9 HYDRAULIC PISTON AND CYLINDER COMBINATION Otto Mueller, 13 Byfield Lane, Dearborn, Mich.

Filed Dec. 6, 1957, Ser. No. 701,207

15 Claims. Cl. 121-33 The present invention relates to a hydraulic piston and cylinder combination and more particularly, to one in which like quantifies of liquid introduced in difierent ports, produce substantially equal but opposite piston travel.

The piston and cylinder combination in the preferred embodiment illustrated is of the swivel type, in which one end of the cylinder is pivotally mounted on a stationary support andthe piston includes a shaft extending outwardly of the opposite end of the cylinder and adapted to be pivotally connected to a shaft or other device, movement of which is to be effected by the piston. In the broader aspects of the present invention it will be appreciated that improvements thereof may if desired be readily incorporated in piston and cylinder combinations which do not involve a swivel action and in which for any reason it is desired to make all the hydraulic connections at one end of the cylinder.

In the preferred construction illustrated, the piston includes two pressure areas at one side of the piston which are efiective upon the application of liquid pressure to them, to urge the piston in one direction, and includes a third pressure area at the opposite side of the piston against which liquid pressure may be applied to urge the piston in the opposite direction. In the construction illustrated, these pressure areas are so proportioned that when liquid pressure is applied to all of these areas, the

diflferential area urging the piston in one direction is substantially equal to the difierential area urging the piston in the opposite direction when pressure is applied only to the second and third pressure areas. The piston and cylinder define first, second and third chambers associated, respectively, with the first, second and third pressure areas and a passage is provided which at all times interconnects the second and third chambers. A control valve is provided which is movable between a first position in which it connects a first supply port to the second and third chambers, and a second position in which it disconnects the first port from the second and third chambers, and' connects the first chamber to the second and third chambers.

Spring means is provided which yieldably urges the control valve to this second position. One end of the control valve acts as a small piston subject to pressure from the first port which, when applied, moves the control valve from said second position to said'first position against the action of the spring. A second port is at all times connected to the first chamber. Both of the ports are located at the same end of the cylinder and in the preferred swivel cylinder construction illustrated, these ports are formed in the trunnion about which the cylinder swivels.

'The objects of thepresent invention include: to pro-- vide an improved piston and cylinder combination inwhich a single piston may be moved in opposite directions ina cylinder and in which the travel of the piston in one direction produced by introduction of a given quantity; of liquid through a first port, is substantially equal to the portion .58 of the control: valve is disposed in a cylindrical a 2940,42? Ic Patented June 14, 196Q travel of the piston in the opposite direction produced by the introduction of the same quantity of liquid through a second port; to provide such a piston and cylinder combination including first and second effective pressure areas at one side of the piston and a third effective pressure area at the opposite side of said piston and first, second and third pressure chambers associated with said first, second and third pressure areas, and a control valve effective in one position to connect a first port to the second and third chambers and efiective in a second position to disconnect the first port from the second and third chambers and connect the second and third chambers to the first chamber; and to generally improve the design of piston and cylinder combinations to provide a construction which is simple in design, economical of manufacture and reliable and efiicient in operation.

Other and more detailed objects of the present invention will be apparent from a consideration of the following specification, the appended claims, and the accompanying drawing wherein: I

Figure l is a broken sectional view of a hydraulic piston and cylinder combination constructed according to the present invention;

Figure 2 is a sectional view of the structure illustrated in Figure 1, taken along the line 2--2 thereof and showing parts removed;

Figure 3 is a broken sectional view of the structure illustrated in Figure 1, taken along the line 3-3 thereof;

and

form of the invention.

Referring to the drawing, the improved hydraulic piston and cylinder combination of the present invention generally comprises a cylinder generally indicated at 10,

a cylinder head 22 which projects into the end of the, sleeve 16 and is securely held in place by a coupling, ring 24 which engages a co-operating flange 26 on the cylinder head 22 and holds it securely against the outer end of the sleeve 16. The head 22 has a transversely. 6X? tending generally cylindrical bearing portion 28 which receives a trunnion 30 which extends therethrough and is also adapted to extend through suitable supports illust-rated in Figure 1 in broken lines at 32. The trunnion 30 has passages 34 and 36 extending inwardly thereof at its opposite ends which connect adjacent their inner ends with radially extending passages 38 and 40, respectively, which extend outwardly to annular passages 42 and 44 formed in the trunnion 30 and in the adjacent portion of the cylinder head 22. The annular passage 42 connects with a passage 46 disposed centrally of the cylinder head 22 which opens into a small control chamber 48. A control valve housing member generally indicated at 50 is mounted in the cylinder head 22 and extends axially substantially throughout the length of the cylinder sleeve 16. To efiect this mounting, the cylinder head 22 hasan enlarged internally threaded cylindrical portion 52 adjacent to the control chamber48 which receives the externally threaded end portion 54 of the control valve The control valve housing 50 has an Figure 4 is a broken sectional view showing a modifiedv the-control valve housing 50 atthe inner end of the recess 60 and a second position to the right of the position illustrated in Figure 1, in which theopposite'iace of -the flange '58 engages the cylinder head '22 at the shoulder indicated at 64. The left-hand portion of the cylinder head '22, as-illustrated in Figure 1, projects inw-ardly of the sleeve 16 as previously mentioned and in its outer surface carried an O-ring 66 which provides an eflective sealbetween the cyli-nderfhead 22 and the sleeve 16; Annular-recess 68 is provided in 'this end of the head 22 which communicates with the annular passage '44 formed in the trunion 30 and :head- 22 through a pair of passages '70 and 72 formed in the head 22, all of which is best illustrated in Figure 3.

The control valve 14 has a passage 74 extending inwardly of its right-hand end which communicates with a radially extending passage 76 opening outwardly through the control valve and, when the control valve is in the position illustrated in Figure l, communicates with the recess 60in the adjacent end portion of thecontrol valve housing 51}. Extending inwardly of the opposite or lefthand end of the control valve '14, is an axially disposed passage 78 which, adjacent its inner end-communicates with an outwardly extending passage 80 which, in the position illustrated, also communicates with-the recess.

60;? Adjacent its right-hand end, the'control valve-14 carries an O-ring 82 providing a seal between the con- 7 trol valve 14 and the cylindrical control chamber-48 in which this end portion of the control valve is received. The control valve housing 50 has a passage '84-extending outwardly therethrough adjacent the inner end'of the cylinderhead: 22' and'opening at-its inner end into an annulargroove 86. The control valve 14 has an annular groove 88 connected by a passage 90 to its central axially extending passage 78. This groove 88-of the control 1" v asses -tending-passage 116 -which-connects the chamber 114 thereof with the interior of the cylinder at the lefthand side of the piston head 96.

neoted tq thc passage rot the trunnion 3i :acts through the passages 38, 42;and 46 and the icontrol chamber 48 against the adjacent end of the control valve 14 to hold it in the position illustramd, against the "action of the spring 92 rs u 1 h -s h j When it is desired omove the piston head 96 to the left, from the position illustrated in Figure 1, pressure is no longer applied through the line 118 but rather, is applied through the line 120 shown in the lower righthand portionof Figure 1 and acts through the passages 36, 40, 44, 70 and and the recess 68, against the-righthand face of the piston head 96. The control valve 14 at this time is in the right-hand position referred to above in which its flange 58 abuts the shoulder'64 on the cylinder head 22, the control valve having been moved to position by the spring 92. In this position the passages--76'and '8'0 are closed off and accordingly, the line 118 is disconnected from the passage 78 in the control valve. This passage 7-8 on the control valve 14 communicates with the chamber 114 in the piston shaft 100 50 is provided with an annular groove 124- in its outer valve 14 is'disposed to be aligned with the groove 86, of the control; valve housing when the control valve- 128, sothat even when the piston head 96 is at the right- 14- has been moved to the right to the position above mentioned in-which the flange ;58;thereof abuts the sho'uh der- 64 on-t-he cylinder head 22. The control valve 14-is u'r-ged-tofthe position-just;described, in which the'flangc 58-engages-the shoulder-64 by-3a coil spring 92 which is V disposed the. control valve housing '50 with' itsleft-hand end engaging a shoulder 94 provided 'onthe control valve housing and its right-hand endengaging @thecontrol'valve 14.- J 1 1 ''pis'ton aarnc ed s a piston-head 96 slidablyfitting theicylindr sleeve-16- and provided with suitable piston rings-98 anda pistonshaft- 160 which extends outwardly i through and is slidably supported in a cylinder end memher 102 which is mounted'on the left hand end of the sleeve- 16- a coupling ring 104- whieh engages the surface into which the radial passage 34 opens, and that the cylindrical-recess 1-26 in the right-hand face-of the piston head 96,- which receives this portion of the cont-rolvalve-housing S0,- is connected to the right-hand face of thepiston head 961 b a chamfer indicated at handf-limit of'its travel,a's-slrown in Figure-l, the passage 8440f" the control-valve housing 5.9 is at all times connected to the recess-68 in-the adjacent raceof the cylindenhead- 22. As pressure is applied in the recess-68 from the-line 120 through-the passages above mentioned, the piston head moved to. the left and the liquid withinthecylinder-sleeve 16.-at the left-hand side of the piston-1head96, and between the piston shaft 1% andjth'e eylindersleeve161fiows through the passage 116 into thechamberfll within-the piston shaft 100. It willvber appreciatedthat the decrease in volume of this chamber, indicated'bythereference character'lfiti, at the left-handside. of the piston head 96. and between the piston shaftv 100- and the cylinder sleeve 16, is much threaded-portion 20 thereof. -The} piston shaft 100 may he connected in any suitable way to the work t9 be moved by'the piston.

flu the -preferred embodiment illustrated, the piston shaft 100 carries a fitting 106' connected thereto by a provide aseal-between thepist on head 96'and-thecon tro'l valveVhoHsing-SG, the left 'handendportionof which r stud 1-08 and the outer end portion ofwhich has a; hearing I10 adapted 'to receivea-trunnionto be movedhg 'the piston. ;The piston 12 is recessed'to receive the con trol valvehousing Sit-and has 'afpairfof" brings 1-12- mounted in the innersurface of the piston head- 96which greater than the increase in volume of the chamber'114 within-the piston shaft 100 which resultsfrom the withdrawIal of'the vendportion of the controlivalve housing 50 -f-rom this-chamber 114 as the piston 12 movestto the left. differential resultsin a flow of liquid from the chambenlllithrough the =passage.122 in the control valve housing 50',- the passages 18 and fiil of the control valv;14,. t-he passages.86;andi84 and'the groove 124 of the-"control valve-housing 50to the right-hand side of the piston. head 9.; It will: thus be. appreciated that. during 7' thismovcmentof theupiston'l2 to the left, the-increasing 'w'elhw in part by-liquid .supplietthrougltfthe line 120 audits-commute the-recess 68..

' jecent the left-hand facesof the piston heath-96, the onishaitlflfl is presided with a generaliy 6&1,

. Itisle teat me-of present applicants' vention that a-g'iv'enquantity of -liquid-introdnced through the line produccamovementofjthe piston 12 tome-left- 'whigh is substantially equal to the movement of the piston to the right, which will be effected by introducing the same quantity of liquid through the line 118. This is accomplished by providing a difierential pressure area efiective to urge the piston in one direction when pressure is hydraulically applied thereto which is substantially equal to the differential pressure area efiective to urge the piston in the opposite direction when pressure is applied to this latter differential area.

In the preferred embodiment illustrated in Figure 1, as the piston 12 is moved to the left, as above described, it will be appreciated that the liquid applies pressure to the right-hand face of the piston head 96 over the annular area indicated by the bracket 132 and over the circular area at the end of the chamber 114 in the piston shaft 100 indicated by the bracket 134. At the same time, there is liquid pressure within the chamber 130 exerting pressure against the left-hand side of the piston head 96 over the annular area indicated by the bracket 136 which, of course, opposes the movement of the piston 12 to the left. The differential pressure area, against which pressure is exerted to move the piston to the left, is equal to the annular area 132 plus the smaller circular area 134 and minus the annular area 136. This is for the reason that during movement of the piston to the left, fluid pressure is exerted on all three of these areas. During movement of the piston 12 to the right toward the position shown in Figure l, the chamber at the right-hand side of the piston head 96 is vented through the recess 68 and the passages connecting it to the line 120 and the differential pressure area against which pressure is exerted to move the piston 12 to the right, is the annular area 136 minus the small circular area 134 which opposes this movement to the right.

The above mentioned feature of obtaining equal movements of the piston in opposite directions by introduction of equal amount of liquid through the lines .118 and 120 is obtained by so designing the unit that these differential pressure areas are substantially equal. As a specific example, if the internal diameter of the cylinder sleeve 16 is six and one-half inches, the external diameter of the piston shaft 109 is four and three-eighths inches and the external diameter of the portion of the control valve housing Sti projecting into the chamber 114 is two inches, the differential pressure area eiiective during movement of the piston 12 to the left is as follows. The annular area 132 is 30.041 square inches, the small circular area 134 is 3.142 square inches, and the annular area 136 is 18.150 square inches. It will thus be seen that the sum of the areas 132 and 134, minus the area .136, equals 15.033 square inches, which is the difierential pressure area against which the pressure acts to move the piston to the left. The diiierential pressure area against which the pressure acts to move the piston to the right is the area 136 minus the area 134, and in this specific illustration, is 18.150 square inches minus 3.142 square inches, or a net of 15.008 square inches. It will be appreciated, of course, that if desired, the dimensions may be so chosen that the difierential pressure areas are exactly equal, or so that they have any desired relation to each other, the preferred relation illustrated being that in which they are substantially equal.

Attention is directed to the fact that in the above described sequence of operations, during movement of the piston 12 to the left from the position illustrated in Figure 1, a given quantity of liquid is supplied through the line 12!), and that during this movement there is no flow out through the line 113 which is closed because of the fact that ii uid cannot fiow from the passage 80 of the control'valve into the passage 76 of the control valve, the intermediate portion of the control valve being disposed within the closely fitting control chamber 48 during movement of the piston in this direction.

During movement of the piston 12 to the right, to the position illustrated in Figure 1, a volume of liquid substantially equal to that introduced through the line during the movement to the left, is introduced through the line 118. It will thus be appreciated that in a complete cycle of the unit, a quantity of oil equal to that introduced through the line 120 during movement to the left, and that introduced through line 118 during movement to the'right, must be vented from the unit. This, of course, takes place during movement of the piston 12 to the right, at which time this quantity of liquid flows out of the unit from the right-hand side of the piston head 96 through the recess 68,- the passages 70' and 72, 44, 40 and 36, and the line 120. It is because of the fact that this volume of flow is twice as great as the flow in through the line 118 that two passages 70 and 72 are provided and that the passages 40 and 36, connected to the line 120, are substantially larger than the passages 38 and 34 connected to the line 118.

The preferred embodiment illustrated in Figure 1 also includes means for cushioning the action of the piston :12 as it approaches opposite ends of its travel. As the piston approaches the right-hand limit of its travel, illustrated in Figure 1, an enlarged cylindrical portion of the control valve housing 50, indicated at 142, is received in and closely fits the cylindrical recess 126 in the right-hand face of the piston head 96. This traps liquid in the inner portion of this recess which may escape slowly past the cylindrical portion 142, causing the piston to slowly approach the limiting position illustrated in Figure 1. For providing a similar cushioning at the limit of the move ment of the piston 12 to the left, as viewed in Figure l, the end member 102 of the cylinder has a cylindrical recess 144 formed therein which receives a cylindrical collar 146 formed on the piston shaft 100 and which closely fits the cylindrical recess 144 while permitting a slow escape past this collar 146 of oil trapped in the recess.

Figure 4 illustrates a modified form of the present invention which diifers from that illustrated in Figure 1 in that it illustrates the embodiment of the improvements of the present invention in a piston and cylinder combination in which the cylinder is not a swivel type cylinder. In the construction there illustrated the cylinder head 22 may be connected to a suitable support in any desired manner, not illustrated. The line 118 is shown connected directly to the passage 46 in the cylinder head, rather than through a trunnion as in Figure 1. In the construction illustrated in Figure 4, the lines 7 0 and 72, the latter of which is ahead of the section along which Figure 4 is taken, are interconnected by a cross passage 138 which connects with a larger passage 140 adapted to carry the flow through both the lines 70 and 72, to the line 129 connected thereto.

While only two specific embodiments of the invention have been illustrated and described in detail herein, it will be readily appreciated by those skilled in the art that numerous modifications and changes may be made without departing from the spirit of the present invention.

What is claimed is:

-1. A hydraulic piston and cylinder combination including a cylinder, a piston having first and second pressure areas at one side thereof against which liquid may act to urge said piston in one direction and a third pressure area at the opposite side thereof against which liquid may act to urge said piston in the opposite direction, a first port, a second port, means for directing liquid from one of said ports to all three of said pressure areas simultaneously for moving said piston in one direction, and means for directing liquid from the other of said ports to said third pressure area and said second pressure area simultaneously for moving said piston in the opposite direction.

2. A hydraulic piston and cylinder combination as defined in claim 1 wherein the sum of said first and second areas minus said third area is substantially equal to said third area minus said second area.

opposite side of said piston.

3. Ahydraulic piston and cylinder combination .as defined in claiml including means defining first, second and third .chamhersin which liquid .may be received to apply pressure respectively to said first, second and third pressure areas, and passage means open at all times and interconnecting .said second and third chambers.

4. A hydrauliepiston and cylinder combination as defined in claim 1' wherein'said first named means includes means providing for flow of liquid from saidicylinder at said opposite side of .said'piston to said cylinder at said one side of said .piston. I t

5. A hydraulic piston and cylinder combination as defined in claim 3' wherein said means for directing liquid simultaneously to all three of said pressure areas includes means for providing for flow of fluid from said second fined in claim 6 including means yieldably urging said control valve to said first position.

8. Ahydraulic piston and cylinder combination as de- 7 fined in claim 7 including means responsive to liquid pressure applied through said second port for moving said control valve to said second position. r

9. A hydraulic piston and cylinder combination including a cylinder, a piston rcciprocable in said cylinder, 2.

first port connected to said cylinder at one side of said piston, a second port connected to said cylinder at the opposite side of said piston, and a control valve within said cylinder connected to said ports etfective in one position to disconnect said second port-from said cylinder at said opposite side of said piston and connect said cylin- V der at said opposite side-of said piston to said cylinder at said one side of said piston said first port and said second port being disposed at the same end of said cylinder.

10. A hydraulic piston and cylinder combination as defined in claim 9'wherein the connection of said second port to "said opposite side of said piston includes means defining a passage-through said piston.

11. A hydraulic piston and cylinder combination in-' eluding first and'se'cond ports, a cylinder, a piston reciprocable in said cylinder, means connecting said ports to said cylinder so that a given quantity of liquid supplied through one of said ports will move said piston the same distance in one direction as the same given quantity of liquid supplied through the other of said ports will move said piston in the'opposite direction, said last named means including a control valve effective in one position to connect one of said ports to said cylinder at one side of said piston and in another position to disconnect said one of saidports from'said cylinder and to connect said cylinder atone side of said piston to said cylinder at the 12. A hydraulic piston and cylinder combination including a cylinder having a cylinder head member at one end thereof, a piston reciprocable in said cylinder, first and second fluid passages in said cylinder head member,

means connecting said first passage to the interior of said cylinder at one sideof said piston, means for connecting said second passage to the interior of said cylinder at the opposite side of said piston, :said last named means including a control valve mounted in said cylinder in telescoping relation with said tpiston and movable between a first position in which it is reflective to connect saidsecond passage to theinterior .of said cylinder at said opposite side of said piston and a second position in which it is efiective to disconnect said second passage from the interior .of said cylinder and to. connect said interior of said cylinder at one siderof said piston .to said interior of said cylinder at the opposite side. of said piston.

eluding a cylinder, a piston .reciprocable in said cylinder, aninlet passage, a combination inlet and outlet passage, means responsive to the introduction of a predetermined quantity of liquid through said combination inlet and outlet passage to move said pistona predetermined distance in one direction, means responsive to introduction of a substantially equal quantity of liquid through said inlet passage to move said piston said predetermined distance in the oppositedirection and simultaneously discharge through said combination inlet and outlet passage a quantity of liquid equal to the sum of said predetermined quantity and .said substantially equal quantity, said first named means including means for closing said inlet passage and transferring a quantity of liquid from one side of said piston to the opposite side of said piston.

14. .A hydraulic piston and cylinder combination including a cylinder, a piston reciprocable in said cylinder, an inlet passage, a combination inlet and outlet passage, means defining first and second chambers and having first and second difi'erential pressure areas respectively associated therewith against which pressure may be applied to urge said piston in one direction, means defining a third chamber and having a third dilierential pressure area associated therewith against which pressure may be applied to urge said piston in the opposite direction, means responsive to the introduction of a predetermined quantity of liquid through said combination inlet and outlet passage to move said piston a prequantity, said first named means including means for 7 closing said inlet passage and transferring a quantity of-liquid equal to said substantially 'equalquantity of liquid from said third and second chambers to said first chamber. a

15. A hydraulic piston and cylinder combination as defined in claim '14 including'means defining a continuously open passage connecting said second and third chambers. I References Cited in the file of this patent UNITED STATES PATENTS 523,419 Thorpe July 24, 1894 1,552,768 Smith Sept. 8, 1925 2,343,316 Newkirk Mar. 7, 1944 2,502,547 Adams .et al Apr. 4, 1950 2,703,558 Wilcox Mar. 8, 1955 mun 

